In the past we have lost fish to herons and raccoons, so all summer long we protected the 8 fish in our little pond with netting and chicken wire. It became so messy with leaves and so forth that we decided to bring them inside. In zone 6 in the northeast, it has been unseasonably warm, and I did not want to have to take fish out of freezing waters. We made a frame of 2x12 pine, draped it with pondliner and filled it with what we guess is 100-120 gallons of water.
We brought the fish in (all varieties of goldfish) and lost 2 comets, probably due to difficult handling in catching them. I used to be able to hand feed them, but they are still pretty frightened. We took in some water lettuce and water hyacinth which are doing questionably. The hyacinth is still in a bucket, as I want to see if it does something beside rot. The umbrella plants and elephant ear seem to be doing OK. Does anyone know if there any kind of plant food that is safe for pond fish? The fish have made a mess of the lettuce, but I think they are starting to acclimate to the new home.
We're still in the experimental stage, and I don't know if other people do this. Does anyone have experience with indoor ponds?